Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus for estimating a speed of a user equipment (UE) in a wireless communication system.
Related Art
Universal mobile telecommunications system (UMTS) is a 3rd generation (3G) asynchronous mobile communication system operating in wideband code division multiple access (WCDMA) based on European systems, global system for mobile communications (GSM) and general packet radio services (GPRS). The long-term evolution (LTE) of UMTS is under discussion by the 3rd generation partnership project (3GPP) that standardized UMTS.
A cell reselection procedure may be performed in the 3GPP LTE. The cell reselection procedure allows a user equipment (UE) to select a more suitable cell and camp on it. When the UE is in either “Camped Normally” state or “Camped on Any Cell” state on a cell, the UE shall attempt to detect, synchronize, and monitor intra-frequency, inter-frequency and inter-radio access technology (RAT) cells indicated by a serving cell. That is, when camped on a cell, the UE shall regularly search for a better cell according to a cell reselection criteria. If a better cell is found, that cell is selected. The change of cell may imply a change of RAT. The number of cell reselections may be used for determining a mobility state of the UE. For example, if a large number of cell reselections is detected, it may be determined that the UE moves fast.
The 3GPP LTE can provide a multimedia broadcast/multicast service (MBMS) service. The MBMS is a service which simultaneously transmits data packets to multiple users. If a specific level of users exists in the same cell, the respective users can be allowed to share necessary resources so that the plurality of users can receive the same multimedia data, thereby increasing resource efficiency. In addition, a multimedia service can be used with a low cost from the perspective of users.
It is required that a method of estimating a speed of a UE when the UE perform a cell reselection procedure due to a user service.